1. Field of Invention
The present invention relates to an object water content sensing device and method, and more particularly to a sensing device and method for sensing a water content of an object by contacting the object and a computer program product.
2. Related Art
Contact-type water content sensors in the prior arts have the following types. (1) A sensing element is formed by etching a circuit on an insulating substrate and configuring a chemical substance, for example, a polymer material, on the substrate surface, so as to present a water content of the environment where the sensing element is located through the chemical changes of the chemical substance. (2) A sensing element is fabricated by a ceramic material together with a circuit design, that is, a porous water absorption characteristic of the ceramic in combination with an electric conductivity regulation technique, thereby deducing the water content of the environment where the sensing element is located through the electricity conductivity change of the substance caused by water absorption. (3) The sensing element is combined with an ionic conduction technique of an electrolyte solution, and the water absorption of the sensing element affects a variation of the ionic conductivity of the electrolyte solution, thereby deducing the water content of the environment where the sensing element is located through the variation. (4) The sensing element is combined with a heat transfer technology, and based on the characteristic that water absorbs heat, the variation of the thermal conductivity of the substance caused by the water absorption is utilized to deduce the water content of the environment where the sensing element is located.
However, the sensing element with the chemical substance configured on the surface is formed by combining two electrical pole pieces with the chemical substance, and combining the electrical pole pieces and the chemical substance with the circuit of the insulating substrate to form one piece, which has a rather complicated working process. Likewise, the sensing element adopting the electrolyte solution technique needs preparing the proper electrolyte solution to combine with the sensing element and meanwhile needs analyzing the ionic conductivity of the electrolyte solution, so the fabricating complexity of the sensing element is not low and the cost is high. Secondly, the contact-type water content sensor with chemical substances configured on the surface needs sensing the water content of the target object for example, a soil water content and a powder water content, in a contact manner. However, undesired chemical reactions of these chemical substances may occur due to the long-time contact with the target object, which induces the deterioration of the chemical substances (denaturalization, tendering, pulverization, and so on of the chemical substances). Also, the sensing element of the ceramic material contacts the target object for a long time for sensing the water content of the target object all day long, so ceramic parts of the element easily deteriorates, for example, becomes tender or pulverizes, which reduces the life cycle of the element, and the stability of the element is unsatisfied when sensing the water content. Thirdly, the contact-type sensor when applied in sensing the soil water content has the defects of low element life cycle and deterioration of the element, which causes that the contact-type sensor is difficult to be applied in sensing the soil water content for a long time. Moreover, once the element deteriorates, the measured water content data is abnormal and cannot be used, so the soil water content cannot be accurately measured. Fourthly, the target object like soil has complicated liquid components and the liquid components contain water, but the current water content sensors disregard the impure water components, so the measured water content is questionable.
Therefore, it is a subject needing consideration to provide a water content sensor which is not easy to deteriorate and can be used for monitoring the water content of a target object for a long time.